1. Field of the Invention
The present invention generally relates to a furnace assembly for use in chemical analysis systems and, more particularly to a tubular-type furnace assembly for use in analysis systems utilizing high-temperature pyrolytic techniques.
2. State of the Art
In the field of analytical chemistry, high-temperature pyrolytic techniques are well known for deriving carbonaceous gases and vapors from small samples of liquids or solids by means of "cracking" carbonaceous molecular compounds in the samples by the application of heat. Once formed in a pyrolysis furnace, the gases and vapors can be passed into a detector or otherwise operated upon for analysis. For example, a conventional infrared analyzer may be utilized to determine the carbon-dioxide content of the volatilized gases and that determination may, in turn, be utilized as a measure of the organic carbon content of the initial sample. As another example, a microcoulometric analysis may be made of the volatilized gases.
Usually it is important that pyrolysis be accomplished in a sealed system so that extraneous gases and vapors do not contaminate the volatilized products. However, since typical pyrolysis temperatures reach as high as 1200.degree.C, thermal expansions make it difficult to effectuate reliable gas-tight seals, especially in the pyrolysis furnace. Sealing compounds, for instance, usually cannot endure such high temperatures for prolonged periods. Also, it is difficult at such temperatures to seal materials to one another when the materials have different thermal expansion properties.